Audio is missing on Phone Patch Output Jack on rear panel of unit.Also missing on Pin #1 of Remote Jack on rear.Audio to Speaker and front panel headphones is ok.Can anyone offer a solution to this problem?Thanks,Jim

My "solution" would be to first websearch out the Service Manual and Schematic for the beast, download it and start studying the schematic and any possible Circuit Descriptions in order to find out how and where those Audio Outputs are derived.

Then I'd open the thing up on the bench and start with a visual inspection from output place backwards towards input, looking for any anomalies first, such as broken pcb trace or solder joints underneath audio plugs such as earphone jack that may contain switching, etc.

If a visual brings up nothing, next I would try mechanical methods such as using an insulated Spudger of some sort to introduce mechanical flexing of pcb in the area where the audio goes thru, while monitoring for audio to come in or not. Any relays involved, give 'em a tap with the plastic handle of a small screwdriver while observing audio to see if it changes.

Finally, Audio Signal Tracing may be needed. This can be as simple as an AF amplifier and speaker with a bit of audio coax and a probe with blocking capacitor at input. Tie ground to rig chassis, use the probe to work backwards from the missing audio output, following the schematic, looking for where the audio is heard in the tracer. The stage immediately following that point is now the suspect. Voltage readings, ohmmeter readings, etc. are in order. Of course, if you find Audio at the input to an audio IC, but nothing on the output pin of same IC, suspect the IC itself. An Oscilloscope can also be used for Audio Signal Tracing if you have one available.

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